Thrombosis and thrombocytopenia syndrome: Its triggers and additional insights
Rare Blood Clotting Disorder Linked to Adenoviral COVID-19 Vaccines
Vaccine-induced thrombotic thrombocytopenia (VITT) is a rare but serious complication associated with adenoviral vector COVID-19 vaccines. This condition involves the formation of blood clots (thrombosis) combined with low platelet counts (thrombocytopenia).
Symptoms and Timeline
Symptoms of VITT typically appear within two weeks after the first adenoviral vaccine dose. Common signs include severe headache, abdominal pain, leg swelling, shortness of breath, and neurological symptoms such as vision changes or weakness.
Causes
VITT is caused by an abnormal immune response triggered by the vaccine, where antibodies activate platelets, causing them to form clots. This mechanism resembles heparin-induced thrombocytopenia but occurs without heparin exposure.
Risk Factors
Most VITT cases have occurred in women under 50 years old after receiving a first dose of an adenoviral vector vaccine (such as AstraZeneca or Johnson & Johnson). Pre-existing conditions may contribute, but no definitive additional risk factors have been universally confirmed.
Treatment
Treatment for VITT includes anticoagulation with non-heparin blood thinners to reduce clotting. Intravenous immunoglobulin (IVIG) may be administered to inhibit platelet-activating antibodies. Early diagnosis and treatment are critical to reduce the risk of fatal outcomes.
Prevalence and Severity
VITT is very rare, with an incidence roughly estimated at 1 in 50,000 to 100,000 vaccine recipients of adenoviral vector vaccines. While it can be fatal in rare cases, most affected individuals can recover with proper care.
Thrombosis with Thrombocytopenia Syndrome
Thrombosis with thrombocytopenia syndrome (TTS) is a newly identified condition that was first identified following the administration of a COVID-19 vaccination. TTS can be a symptom of VITT or can occur independently. It is a medical emergency, and treatment includes anticoagulant medications other than heparin, IVIG, and prednisolone.
Vaccine Safety
Despite the rare occurrence of VITT and TTS, many health organizations, such as the American Society of Hematology (ASH), stress that the benefits of vaccination outweigh the risk of developing these conditions or other rare adverse events. A person with concerns about the safety of COVID-19 vaccines may find speaking with a doctor about them useful.
Importance of Early Detection and Treatment
Early diagnosis and treatment are crucial for managing both VITT and TTS. The ASH recommends seeking immediate medical attention if symptoms such as shortness of breath, severe headache, visual changes, back pain, petechiae, easy bruising, bleeding, abdominal pain, nausea and vomiting, leg pain or swelling develop 4-42 days after vaccination.
[1] Centers for Disease Control and Prevention. (2021). Vaccine-Induced Thrombotic Thrombocytopenia (VITT). Retrieved from https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/adenovirus.html
[2] European Medicines Agency. (2021). Blood clots and low platelets after vaccination with Vaxzevria (COVID-19 Vaccine AstraZeneca). Retrieved from https://www.ema.europa.eu/en/medicines/human/EPAR/vaxzevria
[3] European Medicines Agency. (2021). Blood clots and low platelets after vaccination with Janssen (Johnson & Johnson) COVID-19 Vaccine. Retrieved from https://www.ema.europa.eu/en/medicines/human/EPAR/janssen
[4] American Society of Hematology. (2021). Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT). Retrieved from https://www.hematology.org/globalassets/assets/pdfs/2021-vaccine-induced-immune-thrombotic-thrombocytopenia.pdf
- The formation of blood clots (thrombosis) combined with low platelet counts (thrombocytopenia), known as Vaccine-induced Thrombotic Thrombocytopenia (VITT), is a rare but serious medical condition linked to adenoviral COVID-19 vaccines.
- Symptoms like severe headache, abdominal pain, leg swelling, shortness of breath, and neurological symptoms such as vision changes or weakness may indicate VITT, which is triggered by an abnormal immune response following vaccine administration.
- Despite the risk of VITT and TTS (Thrombosis with Thrombocytopenia Syndrome), many health organizations, such as the American Society of Hematology (ASH), advocate for vaccinations, stressing that their benefits in preventing COVID-19 outweigh the associated risks of these conditions and other adverse events.
